1. Field of the Invention
The instant invention is one that is related to that group of devices that function to effectuate remote interrogation via the multiplexing of switching devices.
2. Brief Description of the Invention
The instant invention constitutes a method and apparatus for time division multiplexing a number of optical modulation devices on a limited number of optical transmission paths. This function is accomplished by way of the utilization of electrically unpowered photoactivated optical switches that segmentially direct available optical power to successive points remote in location relative to the locus of an optical power source. The invention consists of control and signal processing electronics, an optical power source, an outwardly directed optical transmission path, a plurality of electrically unpowered photoactivated optical switches positioned along said outwardly directed transmission path, a plurality of optical modulation devices positioned one each apropos each said switch, such that each such device is positioned on each one of a plurality of alternate optical transmission paths, one or more inwardly directed optical transmission paths, a plurality of optical coupling devices (one per optical modulation device) positioned one each along the one or each one of said inwardly directed optical transmission paths, and a photodetector module interfaced as is the invention's power source component with the invention's control and signal processing electronics.
3. Objects of the Invention
Successive interrogations of each one of a series of sensors along a pathway on which they are positioned has heretofore required the use of couplers that are either electrically active or electrically passive. Passive variants can be so utilized at much lower costs than active ones. Moreover, resort to passive variants operates to significantly reduce the effects of any interchannel crosstalk that can serve to greatly enhance the unreliability of collected data transmissions. But, a problem heretofore with respect to resort to such passive variants has been a virtually exponential loss of power directed from a power source with increasing remoteness therefrom along an outwardly directed path as quanta of power would be successively siphoned off by way of the invariable routing of some of the available power at the locus of each such coupler to an alternate transmission path thereby leaving less total power available at the site of the next remote coupler along such outwardly directed path.
The instant invention is virtually revolutionary within the field of such devices, since, it utilizes electrically passive switches rather than couplers that serve to accomplish routing of power along alternate transmission paths without concomitant loss of power available to the next remote switch along the outwardly directed path on which said switches are found. Thus cost and crosstalk are greatly minimized resulting in the concomitant availability of much larger quantities of sensed data from a greatly increased number of sensor sites that is inherently more reliable for much less cost than can be obtained with resort to the utilization of related sensing systems currently in vogue.